A surgical margin defines the visible margin of normal tissue that is removed when diseased tissue is surgically removed. Generally, surgical margins can allow total removal of the diseased tissue while minimizing the removal of normal healthy tissue. For example, when the surgical margin is defined, the presence of satellite disease in tissue surrounding or adjacent to diseased tissue and disease that is propagating through regional lymph vessels and lymph nodes must be taken into consideration.
Historically, surgical margins have been determined based on empirical evidence from a series of patients that illustrates how their tumors propagated both locally and regionally. As data for more patients becomes available, surgical margins have been adjusted accordingly. Alternatively, surgical margins can be determined in situ (e.g., for skin cancer using Mohs surgery). In Mohs surgery, after each tissue removal, the tissue is examined for cancer cells, which informs the decision for additional tissue removal, thereby defining the surgical margin. Surgical margins defined with the Mohs surgery remove less normal tissue and experience fewer disease recurrences. However, Mohs surgery is not cost efficient (e.g., employing multiple ancillary staff, requiring more capital and disposable equipment, and lengthening the intraoperative time). An alternative to Mohs surgery would employ in situ determination of surgical margins in real time, thereby obviating the need for the inefficiencies of Mohs surgery while maintaining or exceeding the sensitivity and specificity of tumor removal.